金属前驱体摩尔比对CZTS纳米晶微结构的影响

Effects of Metal Precursor Molar Ratio on Microstructure of CZTS Nanocrystals

采用热注入法制备Cu_2ZnSnS_4(CZTS)纳米晶,研究了金属前驱体摩尔比对所制备的CZTS纳米晶的晶体结构、化学组分、形貌及光学性能的影响。实验结果表明:当Cu∶(Zn+Sn)前驱体摩尔比在0.8∶1～1∶1范围变化时,所得到的产物为纯锌黄锡矿结构CZTS纳米晶。当Cu∶(Zn+Sn)≤0.7∶1时,产物的XRD图谱在(112)晶面衍射峰附近出现微弱的SnS杂峰。当Cu∶(Zn+Sn)前驱体摩尔比从0.9∶1变化为0.8∶1时,纳米晶的形貌主要为球形,少量为多边形;当Cu∶(Zn+Sn)前驱体摩尔比从0.7∶1减小到0.6∶1时,纳米晶的形貌主要有纺锤形及少量球形。所制备样品的光学带隙随着Cu∶(Zn+Sn)前驱体摩尔比的减小而增大,其带隙宽度在1.44～1.56eV之间变化。

Cu2ZnSnS4(CZTS) nanocrystals (NCs) were synthesized by hot injection method, the influence of the precursor molar ratio of Cu∶(Zn+Sn) on the crystal structure, chemical composition, morphology and optical properties of CZTS was studied. The results indicate that the CZTS nanocrystals are pure kesterite structure when the precursor molar ratio of Cu∶(Zn+Sn) changed from in the range of 0.8∶1 to 1∶1. When the precursor molar ratio of Cu∶(Zn+Sn) is not more than 0.7∶1, the XRD patterns of the product show a weak SnS peak near the (112) crystal plane diffraction peak. When the precursor molar ratio of Cu∶(Zn+Sn) is changed from 0.9∶1 to 0.8∶1, the morphology of the nanocrystals is mainly spherical and a small nanocrystals is in the shape of polygonal; when the precursor molar ratio of Cu∶(Zn+Sn) is from 0.7∶1 to 0.6∶1, the morphology of the nanocrystals mainly takes the shape of spindle and a small amount of nanocrystals is spheres. The optical band gap of the prepared sample increases with the decrease of the precursor molar ratio of Cu∶(Zn+Sn), and the optical band gap varies from 1.44eV to 1.56eV.